Added Raspberry Userland

[burnbabyburn]

• Get vcgencmd back (Code from here)
• Added same logic for videocore as in uboot (compile existing src or clone repo)
• Added ENABLE_VIDEOCORE, VIDEOCORESRC_DIR and VIDEOCORE_URL variable
• Some improvements (escaped variable, use -n instead of !-z in if-conditions)
• fixed missing $ beofre NTP1

[drtyhlpr]

great pull and thanks for corrections. I did not even know about the availability of raspberry userland+